Our immediate goals are a detailed analysis of the radiation response and combined-modality response (i.e. adriamycin and x-irradiation) of two established in vivo lines (Slow and S102F) of the C3H mouse mammary tumor as well as that of the lining epithelium of the duodenal crypts. These analyses will be especially concerned with evaluating the therapeutic responses as they relate to the various growth kinetic parameters in the belief that such an approach will suggest a simplified model for optimizing protocols for fractionated radiation therapy and fractionated combined-modality therapy. The method of analyses included growth delay, TCD50/120, 3H-TdR autoradiography and flow cytometry. These analyses will be for tumors x-irradiated under ambient (mice breathing air), hyperbaric oxygen and/or mixtures of oxygen and carbon dioxide, and hypoxic (tumor circulation clamped) conditions. The analysis for the duodenum includes LD50/6, crypt survival 3H-TdR autoradiography and flow cytometry. These studies on both normal and malignant tissues are done for adriamycin alone, x-irradiation alone and combined treatments with various intervals of time between modalities.